Bicycle Mechanics - Derailer pulley too close to freewheel

Hey. Until about 3 hours ago I was using a mishmash of a crappy cottered crank, a shimano 5-speed SIS shifter, a Shimano 7-SIS derailer, and a Falcon 6 speed hub. I had adjusted the derailer L/H and it was working ok, but I wanted to try to get everything to the same number of gears. Today I swapped the cottered crank for a Shimano Acera triple (I only use one) , traded the freewheel for a SunTour "perfect" 5-speed and now its worse than before. 5, 4, and 3 work ok, but then 2nd gear jumps all the way to the largest ring, and 1st knocks it off the hub entirely. I also notice when the derailer is in 1st gear, it's practically touching the largest ring on the hub. Is this normal? I don't remember it being like that before.

I tried adjusting the L-screw on the derailer, but it doesn't look like it'smoving at all. H-screw seems to be doing it's job fine.

Think it could have gotten bent somehow?

I was trying to see if the 7-SIS derailer had a b-tension adjustment screw, but I don't see one anywhere.

Any ideas?

Vincent

Nope, probably just the whole drive train getting ready to implode on you. Sounds like it is new drivetrain time. 5,6,7 speed stuff mixed together is asking for odd shifting and immature failure of the drivetrain. Drivetrains need a constant two combos let's say 8 and 9 will work but a 7 on a 5 with that sitting on a 6 will not work. I'd go up to 7 speed if your bike can handle it.

Hey. Until about 3 hours ago I was using a mishmash of a crappy cottered crank, a shimano 5-speed SIS shifter, a Shimano 7-SIS derailer, and a Falcon 6 speed hub. I had adjusted the derailer L/H and it was working ok, but I wanted to try to get everything to the same number of gears. Today I swapped the cottered crank for a Shimano Acera triple (I only use one) , traded the freewheel for a SunTour "perfect" 5-speed and now its worse than before. 5, 4, and 3 work ok, but then 2nd gear jumps all the way to the largest ring, and 1st knocks it off the hub entirely. I also notice when the derailer is in 1st gear, it's practically touching the largest ring on the hub. Is this normal? I don't remember it being like that before.

I tried adjusting the L-screw on the derailer, but it doesn't look like it'smoving at all. H-screw seems to be doing it's job fine.

Think it could have gotten bent somehow?

I was trying to see if the 7-SIS derailer had a b-tension adjustment screw, but I don't see one anywhere.

Any ideas?

Vincent


1 .Without going into a lot of explination about indents and pivot point lengths and the possibility that rear cogs are spaced differently I would suggest you go to a friction shifter.

2.You want the pulley close to the cog.

3. On top of eveything else the derailer is probably bent. I tried out 4 sis's on my crap bike and only one was strait. Still shifts like crap. Same as the bent ones.

4. Find a narrow chain.

A couple of suggestions:

If the chain is coming off the cogs altogether then you need to adjust the limit screws to prevent the derailer from getting too far over. If the L limit screw isn't working then you need to find out why. A chain slipping off the largest cog can cut spokes and send you flying.

You will probably never get this arrangement to work correctly in index mode. I suspect that the 5-speed shifter and the 7-speed derailer are not compatible and the derailer moves too far for every click of the shifter. If so, can you put the shifter into friction mode (no clicks?) That will allow you to shift correctly.

It may never work perfect, as you're using a non-sis freewheel. Also, it sounds like you may be using a freewheel whose biggest cog your derailleur can barely handle, if at all. The 5-speed indexed shifters are usually pretty junky and the benefit small over 5 speeds. And mixing used/new freewheel/chain is generally a bad idea. But you can try these steps to make it work.

1. Detach the cable from the derailleur.

2. Adjusts L limit screw so that the upper pulley lines up with the small cog. Look at the derailleur from up and behind. if the pulleys and cog do not line up, your hanger is bent. You can try to bend it back but DO NOT GRAB IT BY THE PULLEY CAGE (this is assuming you're using a derailleur with a claw). Hold it by the upper assembly, or better yet try to find something to grip the claw itself. Align and readjust limit screw as necessary.

3. Put shifter in hardest gear, screw adjusting barrel on derailleur down most of the way and reattach cable. Shift 1 speed while pedaling. if it doesn't shift up, back off barrel adjust until it does. Work up to big cog doing the same thing. Adjust H screw so that it doesn't run off the big cog.

If the upper pulley still grazes the big cog, taking a link out of the chain may make it work.

Is the large cog on the new freewheel bigger (more teeth) than its predecessor? If so, that would account for the der being so close to it. JAT.

If I inderstand this correctly, when the chain is on the largest rear cog, the upper most derailleur pulley is just about touching the cog? Assuming this is the case, there is an adjustment on the derailleur for this condition. There is a screw on the derailleur with the screw head towards the rear of the bike. When screwed clockwise, it moves the derailleur away fromn the cog and towards the rear of the bike. When the screw is turned counterclockwise it allows the derailleur to move foward towards the front of the bike. In the bike maintenance manuals that I use for reference, this screw is there specifically to position the derailleur with the correct front to rear aspect ratio without allowing the upper pulley to come in contact with the largest cog.